The present invention relates to fuel rail assemblies and, more particularly, to fuel rail damping devices wherein the damper is open to atmosphere.
Many modern automobiles incorporate fuel injected engines which require a high-pressure fuel feed upstream of the fuel injectors. The fuel injection system incorporates a plurality of injectors that deliver fuel to the inlet ports of the engine. The injectors are mounted in a fuel rail that supplies high-pressure fuel to the inlet side of the injectors. Most fuel injected engines use electromagnetic fuel injectors, one injector per cylinder, which deliver fuel in metered pulses that are timed to provide the amount of fuel, needed in accordance with the operating condition of the engine.
The cyclic operation of the electromagnetic injectors induce pressure pulsations in the fuel rail which may have a detrimental affect on the operation of the fuel metering system. To reduce the effect of the pressure pulsations, automotive designers have incorporated dampers into the fuel system. Damping systems known in the art add compliance to the fuel injection system by adding devices such as internal rail damping systems or external rail damping systems.
One type of external damping system incorporates a spring diaphragm device; an o-ring sealed interface to the rail, a retaining clip, as well as multiple stamped parts that form the interface to the rail. Internal damping systems that provide a closed and atmospherically pressurized vessel within the fuel rail have fewer parts than an external damping system. However, in the conventional internal damping system, the damper must be assembled into the rail after the components of the rail are brazed together since the extreme temperatures in the braze furnace would cause the air trapped in the damper to expand and thereby cause permanent deformation of the damper walls and render the damper ineffective. The necessary post-braze assembly operation of the damper to the fuel rail adds labor, and additional parts including an o-ring sealed end plug and a retaining clip. This may also increase costs and reduce reliability of the fuel rail assembly. U.S. Pat. No. 5,617,827 issued to Eshleman et al. on Apr. 8, 1997, the disclosure of which is incorporated herein by reference, discloses a fuel rail that includes a conventional internal fuel rail damper.
What is needed in the art is an internal damper which can endure the temperatures of the brazing operation and therefore can be assembled into the fuel rail before the brazing process is completed.
A fuel rail damper which includes a hollow member having a first end and a second end, and at least one active portion. At least one of the first and second ends being open to atmospheric pressure and extending outside the fuel rail to thereby define a chamber in conjunction with the active portion.